Method of making rib-back blades



Dec. 19, 1939.

M. PARKER ET AL METHOD OF MAKING RIB-BACK BLADES Filed July 1935 W 1 11/ 4, III I 2 Sheets-Sheet 1 I//IIIIIIIIII/IIIIIIIIIIIII/I/IIIIIIIIIIIIIIIIIII4 ///IIIlIII/IIIIIIIII II/IIIIIIIIIIIIIIIIIIIIIIIII4 A W, 1939. M. PARKER ET AL 2,184,150

mvrfion OF MAKING RIB-BACK BLADES lfiled July 51, 1935 2 Sheets-Sheet 2 I11 vewfior Patented Dec. 19, 1939 UNETED STATES PATENT oFFicE METHOD OF MAKING RIB-BACK BLADES,

poration of New York Application July 31, 1935, Serial No. 34,012

10 Claims.

This invention consists in an improved method of manufacturing rib-back blades from strip steel. For purposes of illustration the invention will be described in its application to the manufacture of rib-back surgical knives, although it may be advantageously practiced in the manufacture of any fine-edged blade in which a ribback is desired.

The method of our invention is characterized, first by the rolling of steel strip to compact it to form therein parallel ribs of symmetrical shape and arrangement, and second, by the formation of the cutting edge portions of the blade from the body of the ribbed strip where the metal has been compacted and thus best adapted, by reason of its rolling treatment, to serve as a cutting edge.

We have discovered that many advantages flow from the step of forming ribs, or a double rib, in the steel strip. The strip is in this way maintained at all times in a straight condition, whereas in forming a single rib or an unsymmetrically located rib in strip stock there is a pronounced tendency to curve or camber the stock. Then, in forming a double-ribbed strip the material of the strip body is particularly well prepared to serve as edge-carrying portions of the blade. This may be because of the lines of flow to which the steel of the body of the strip is subjected in rolling and to the close grain structure thus produced, but whatever the cause, an improved quality of cutting edge results. Further, ribbed stock of symmetrical cross section may be handied, coiled and uncoiled with convenience in all the various processes of manufacture to which it is subjected and may be fed in a balanced manner to punch presses and the like. Ribbed stock of this kind, moreover, may be evenly heated and cooled in the processes of hardening and tempering, and is not likely to become overheated in localized areas. Finally it may be cut up into individual blanks with particularly good advantage in economy, the back of the blanks including sections of the ribs of the strip and the edge-carrying portions occupying the body of the strip.

In a preferred manner of carrying out our invention the blade-strip is provided with marginal ribs in its opposite edges since this arrangement facilitates the rolling operation in some respects and also provides material which may be cut up with minimum waste and with structural advantage to the individual blades. In cutting up such a marginal ribbed strip the blades are preferably outlined in the strip with the back of each blade blank including a section of one of the marginal ribs and the edge-carrying portions of the blank lying in the body of the strip in opposed relation to an oppositely disposed blank, that is, when the strip is of suflicient width 6 to include two lines of blade blanks. In manufacturing blades of certain styles, however, it may be advisable to outline a single line of blanks only and under such circumstances one rib may be trimmed from the strip, or the strip 10 may be split longitudinally and the blade blanks outlined as single rows in each half of the single ribbed strip thus produced.

The problem of producing a straight, ribbed strip of symmetrical and uniform cross section 15 in thin flexible strip steel has been solved by our invention. Starting with a flat strip or ribbon we roll the stock in such a manner as to produce therein a reduction of thickness in the body of the strip, a reduction in its width, a thick- 20 ening of its marginal edges into ribs or beads exceeding the thickness of the original stock, and also an elongation of the strip. These changes in dimensions and shape are brought about by causing the stock to flow both outwardly in the 25 body of the strip and inwardly from the margins thereof. It will be apparent that by that procedure, we avoid drawing out a thin marginal edge which is likely to be over-rolled or to contain minute cracks and so be unsuited for 30 cutting edge material. On the contrary, we consolidate the metal of the strip in marginal ribs or beads and maintain the body thereof intact and rolled into a close-grain condition which adapts it particularly well for cutting edge ma- 35 terial.

Having prepared the strip stock in the manner above explained the individual blanks may be defined by properly perforating and scoring the strip and it is generally advantageous to carry out this step and to sever the bead between adjacent blanks while the steel is still in untempered condition. Thereupon the perforated strip may be hardened and tempered by any preferred process of strip treatment. The advantages of maintaining the blade blanks in strip form for the tempering operation is obvious in respect to economy of operation and uniformity of product. Moreover this sequence of steps facilitates the separating of individual blanks since in tempering the strip is rendered sufficiently brittle to break easily and accurately upon the scored lines which have previously been impressed in the softer material of the untempered strip.

Our invention is characterized by various other novel steps carried out in connection with the tempered blanks in polishing them, in bringing them to final shape and in forming the cutting edge thereon, although these steps are more or less optional and may be varied or modified as desired. For example, we have found it advantageous to separate the continuous strip as it leaves the tempering furnace into a plurality of shorter lengths and to polish these lengths while held in a fiat and straight condition in a suitable strip holder. a plurality of blanks in a jig or gauge block for uniformly grinding certain portions of the blanks and to thread them upon a mandrel for further grinding those edges which cannot be conveniently reached while these blanks are located in the jig. These steps are economical and advantageous, particularly as supplementing the earlier steps of providing symmetrical ribs in the strip, defining the individual blanks therein and tempering the blanks in strip form before separating them.

These and other features of the invention will be best understood and appreciated from the following description of a preferred manner of putting the method into practice as illustrated in the accompanying drawings, in which- Figs. 1, 2, 3, and 4 are views in perspective of a portion of the steel strip in its initial form and as modified by three successive rolling operations,

Fig. 5 is a view in front elevation of the rolls,

Fig. 6 is a fragmentary view on an enlarged scale, showing a portion of the strip as acted upon by the rolls,

Fig. 7 is a plan view of the ribbed strip showing successive steps of the operation of defining the individual blanks therein,

Fig. 8 is a diagrammatic view illustrating the hardening and tempering steps which are performed on the strip.

Fig. 9 is a view in perspective illustrating the polishing step of the method,

Fig. 10 is a plan view of one of the blade blanks separate from the strip,

Fig. 11 is a view in perspective of the jig or fixture with blade blanks held therein for the first grinding operation, showing also the mandrel,

Fig. 12 is a view in perspective of a stack of blades in position upon the mandrel, and

Fig. 13 is a view in perspective of a finished rib-back blade.

In carrying out the method of our invention we prefer to employ high carbon steel having a small percentage of chromium in its composition. For purposes of manufacturing the rib-back blade herein shown, this may be procured as strip stock .025" x .850 in dimension and coiled in strips of any convenient length. In Fig. 1 is represented a portion of the strip stock and this is thin and flexible in its characteristics, being stock of an order of thickness not modified by rolling in the cutlery industry heretofore.

The strip stock is first subjected to progressive rolling operations in a rolling mill of the general character illustrated in Fig. 5 and in which is employed a pair of rolls l4 and I6 arranged to rotate about parallel horizontal axes and being shouldered at each end to form portions I5 and l! respectively of reduced diameter which are effective to relieve pressure upon the edges of the strip during the initial rolling steps. The mill also includes a pair of rolls l8 and 20 arranged to rotate on vertical axes and to en- We also prefer to assemble gage the opposite edges of the strip as it is passed between the rolls l4 and I6 and to compress the strip laterally and upset its marginal edges where they are not confined between the body of the rolls M and 16. It will be understood that both sets of rolls are arranged for adjustment toward and from each other, and that the setting of the rolls is very carefully adjusted during the process of treating the strip and between successive passes thereof.

As indicated in Fig. 2 the first rolling step slightly reduces the thickness of the body of the strip, reduces its width and creates a slight bead along its opposite marginal edges. In this step also the strip is somewhat elongated. In dealing with the strip herein shown the first step may reduce the thickness of its body from .025" to .020 and its width from .850 to .820. At the same time marginal beads having a thickness approximately .030 are formed in each edge of the strip. In the second rolling step the thickness of the body of the strip may be further reduced, to approximately .0175, and its width to .812". Simultaneously the thickness of the bead may be increased to .032. In the final rolling step the body of the strip may be again reduced, for example to .015, and its width to .800", while the thickness of the bead is increased to .036".

It will be understood that these dimensions are stated as illustrative only of one satisfactory manner in which the steps of the rolling process may be carried out, and in no manner as limiting the invention. In carrying out these steps however, it is important to produce a continuous strip of symmetrical cross section in which the body part has been consolidated by pressure and without any tendency to contain incipient transverse cracks which would be objectionable in the cutting edge of the blade. On the other hand, a strip or continuous tempering step is essential to the method of my invention and it is therefore necessary to employ strip steel of a thickness adapted for progressive quenching between chilled plates. Steel of a thickness of .025 inch may be taken as one example of a suitable material, being well adapted for treatment in commercial apparatus. As will be apparent from Fig. 6 the body 10 of the blade is subjected through the rolling operation to a compacting action by the rolls I4 and I6 and on account of the fact that the rolls I8 and 20 prevent this material from fiowing transversely. The action of the side rolls is to force the material of the strip inwardly so that the major part of the fiow to which the strip is subjected is in a longitudinal direction and more or less parallel to the sharpened edge which is eventually to be formed into individual blades.

As will be noted in Fig. 6 the cross sectional area of the space between the reduced or relieved portions l5 and I! of the surface rolls l4 and I6 and the cooperating edge roll IB is slightly in excess of the cross sectional area of the finished bead or flange 12 upon the strip. This relationship of the rolls is important in that it obviates the formation of fins at the outer corners of the bead and leaves the contour of these corner edges curved upon a short radius. This condition is illustrated with some exaggeration in Fig. 6 and while not essential, is a useful and convenient feature of our invention. As will be understood from the foregoing description the product of the rolling steps is a continuous strip of steel fiexible and somewhat resilient in its 76 character, with its body portion ll) of fine grain compacted by rolling and symmetrical marginal beads i2 of approximately twice the thickness of the body portion it.

The strip produced by the rolling steps is next subjected to the step of having the individual blade blanks defined therein. This may be effected by passing the untempered strip stepby-step through a die press having appropriate dies properly arranged and spaced therein. The die press is not herein shown since commercial machinery may be utilized for this purpose, but the successive steps of the operation are indicated in Fig. 7 of the drawings. As suggested in this figure the first step of the process may consist in scoring the short oblique transverse marks or corrugations 22 at opposite edges of the strip just inside the bead i2, punching the oppositely arranged apertures 2t and stamping the numeral 2i which is to constitute the blade designation. In the finished blade the line 22 is to determine the rear inclined edge of the blade shank or butt and the aperture 2% is to fit a corresponding projection in the handle of the blade knife. Accordingly in the finished blade this dimension is of importance, that is, the distance between the mark 22 and the end of the aperture 2 3 must be accurate and therefore the mark and corrugations are formed simultaneously in the first step of the defining operation. In the second step of this operation the parallel longitudinally inclined marks or corrugations 26 are formed in the blade between oppositely disposed apertures 2 and the letters U. S. A. or any other designation are stamped upon the strip in the proper position. In the third step of the defining operation the cut outs 28 are punched by suitably shaped dies and this, as will be apparent, defines a portion of the curvature of the cutting edge of two blanks and the curvature of the shank of two other blanks. In this step also are formed the triangular notches 30 severing the bead i2 and coinciding at one end with one of the marks 22. The notches 39 are of importance in determining the shape of the blade back, and also in facilitating the subsequent breaking up of the strip and the separation of the individual blanks. The general shape of the blades is determined by the shape of the cut-outs or perforations 28 and, as herein shown, each of these comprises two reversely curved segmental portions connected by an enlarged central opening which includes oppositely arranged angular corners. The segmental portions extend in opposite directions from the central opening and the adjacent ends of consecutive segments are spaced by the length of the parallel marks 26.

From the foregoing description it will be apparent that in Fig. 7 the right hand end of the strip is represented in the condition in which it leaves the rolling mill and the left hand end is represented in the condition in which the blade blanks are fully defined therein. It should be noted, moreover, that the scoring and punching operations just described are effected in the unhardened strip.

The scored and punched strip prepared as shown in Fig. 7 is now recoiled and then subjected to the hardening and tempering steps as illustrated in Fig. 8. The strip is drawn from the coil 32 by feed rolls 40 through an elongated furnace 3i which may be heated by gas or electricity and in which the temperature of the strip is raised to the critical point of the material,

for example, to about 1500 degrees F. Upon leaving the furnace 34 it is passed between water cooled quenching plates 36 and is thus hardened. Subsequently it is passed through a tempering furnace 38, and drawn at a temperature of from 350 degrees to 4'75 degrees F. to a temper appropriate for fine cutting edges.

As the perforated and now tempered strip leaves the furnace 38 it is inspected and broken up by an operator into lengths 42 each about 18 inches long, and is advanced for further treatment in this condition. The tempered strip may be easily broken across upon any pair of scored lines 22, which, it will be noted, are arranged in alignment with each other, intersecting the cutout 23 on its greatest transverse dimensions, and coinciding with the edged notches 30 in the bead of the strip.

The short lengths 52 are preferably immediately immersed in oil to safeguard them against rusting, and are subsequently subjected to a polishing operation which may, if desired, be carried out as suggested in Fig. 9. For this purpose four lengths 42 of the perforated and tempered blade strip are placed in a blade container i l provided with a series of parallel grooves 46 for the reception of the marginal beads l2. The beads fit within these grooves and hold the lengths 42 firmly in place and maintain them in fiat condition. While thus positioned they are passed progressively beneath a rapidly rotating wire brush, 48, which is eiiective to remove any surface discoloration, imperfections, scratches, oxidizing spots or the like from the material of the strips. The strips are carefully inspected at this stage and may be now broken up into individual blanks 50 of the character shown in Fig. 10.

The blanks 50 are now ready to be assembled in a grinding jig 52 such as that illustrated in Fig. 11. This comprises a block having parallel slots 54 for the reception of the individual blade blanks and longitudinal gauge shoulders 56. The blanks 50 are positioned roughly in the jig which holds them in parallel alignment, and while in this condition a mandrel 58, which is tapered at one end, is inserted through the aligned apertures 24 thus locking all the blades in the relation established by the slots and shoulders 56 in the jig.

The blades are next subjected to grinding operations, first along the back and then along the short inclined edge Ed, to round off and smooth the juncture formed between these two intersecting planes, and then across the rear ends of the blade shanks to true them. While the blanks are so held it is also convenient to remove any grinding burr which may have been formed, by passing the assembled blades over a wire brush. The stack of blades is then removed from the jig 52 upon the mandrel 58, whereupon the curved side of the blade points may be ground to shape and to remove the excess of material left at the sharp end of the blade when it is separated from the strip on the line 22 and convert that line into a part of the continuous sharp cutting edge of the finished blade.

After the various grinding operations to perfeet the shape of the blanks have been completed, the blanks are removed from the mandrel 58 and sharpened one by one to produce the finished blade shown in Fig. 13. As will be seen from the foregoing description the blade 60 has a sharpened edge portion 6| which has been formed from the compressed steel of the body In of the strip. It is provided with the aperture 24 and with the rib 63 which forms the back of the blade, stiffening and so reinforcing it against breakage, providing a relatively wide surface to be engaged by the rubber glove of the surgeon, and supplying also a relatively stiff axis of tortion for bending which may take place in that part of the blade set off by the aperture 24 in attaching the blade to and removing it from the handle with which it is to be used. The inclined edge 64 or hook is characteristic of the particular blade herein shown and may or may not appear, depending upon the type of work for which the blade is desired.

The present invention includes within its scope the novel blade herein shown as produced by the method of our invention, that is to say, a blade made from a sheet metal blank with a preformed flange therein and including a portion of such flange as a solid rib in its back.

While our invention has been disclosed herein in its application to the manufacture of detachable blade for use in surgical knives, it will be understood that its field of use is not so limited but that it may be carried out advantageously in the manufacture of any blade of a type wherein the ribbed back is a desirable feature, safety razor blades being another specific example of such blades as we have in mind.

Having thus described our invention what we claim as new and desire to secure by Letters Patent of the United States is:

1. A method of making rib-back surgical blades, which consists in rolling a thin flexible strip of steel to produce therein symmetrical marginal ribs, forming curved perforations in the strip partially outlining oppositely arranged blanks in the strip with the back of each blank including a straight part of a marginal rib, progressively hardening and tempering the perforated strip, then separating the blanks from the strip, each with an edge portion partially curved and partially straight, and finally grinding to give a full curve to said portion.

2. A method of making rib-back surgical blades, which consists in rolling a thin flexible strip of steel to produce spaced ribs therein, perforating the strip and. thereby outlining blanks which include part of a marginal rib and an edge portion which is partly curved and partly straight, hardening and tempering the strip, separating the tempered blanks, and then grinding to produce a continuously curved cutting edge therein.

3. A method of making rib-back surgical blades, which consists in rolling flexible strip steel of an order of .025 inches in thickness to reduce its width and form a longitudinal rib therein, perforating the strip to form reversely curved connected segments partially defining individual blanks so located as to include a portion of said rib, tempering the strip, separating the tempered blanks each with a cutting edge portion partially curved and partially straight, and then grinding to produce a continuously curved cutting edge therein.

4. A method of making rib-back blades, which includes the steps of rolling untempered steel strip which is approximately .025 inch in thickness to form therein a longitudinal bead and a compact body portion, notching the bead in accordance with the length of the blade blanks desired, cutting in the strip a series of perforations each having narrow segmental portions merging into a wider central opening, said perforations partially defining blade blanks in the strip which include portions of said bead, then tempering the perforated strip, subsequently separating the tempered strip into individual blanks, and grinding to shape a continuous cutting edge therein.

5. A method of making rib-back surgical blades, which consists in rolling a thin strip of steel to produce therein symmetrical longitudinal ribs, forming curved perforations in the strip partially outlining oppositely arranged blanks in the strip with the back of each blank including a straight part of a longitudinal rib, progressively hardening and tempering the perforated strip, then separating the blanks from the strip, each with an edge portion partially curved and partially straight, and finally grinding said edge portions to form a cutting edge.

6. A method of making rib-back surgical blades, which consists in rolling thin strip steel to form an untempered strip approximately .015 inch in thickness having symmetrical longitudinal ribs therein, forming perforations in the strip partially outlining oppositely arranged blades in the strip with the back of each blade including a straight part of a longitudinal rib, hardening the perforated strip by quenching it between cooled plates, tempering the strip, then separating the blanks from the strip each with an edge portion partially curved and partially straight, and finally grinding said edge portions to form a cutting edge.

'7. A method of making rib-back surgical blades, which consists in rolling a thin strip of steel to produce therein symmetrical longitudinal ribs, forming perforations in the strip partially outlining oppositely arranged blanks with the back of each blank including a straight part of a longitudinal rib, hardening and tempering the perforated strip, polishing the tempered blanks while supported in strip form and held in fiat condition, then separating the blanks from the strip, each with an edge portion partially curved and, partially straight, and finally grinding said edge portions to form a cutting edge.

8. A method of making rib-back surgical blades, which consists in rolling a strip of steel to produce therein symmetrical spaced longitudinal ribs, forming curved perforations in the strip partially outlining oppositely arranged blanks each including a straight part of a longitudinal rib and having a straight transverse line of separation at both ends, hardening and tempering the perforated strip, then separating the blanks from the strip, each with an edge portion partially curved and partially straight, and finally grinding said edge portions to form a cutting edge extending to one end of the blade while the straight edge at the other end defines the butt of the finished blade.

9. A method of making rib-back surgical blades, which consists in rolling strip steel about .025 inch in thickness under edge and surface pressure to reduce the body of the strip without increasing its width and at the same time to form symmetrical longitudinal ribs therein, punching and scoring the strip to form blade blanks, each with an edge portion partially curved and partially straight, said blanks being separated by parallel oblique scored lines and including a rib section, hardening and tempering the scored strip, separating it into tempered blade blanks, and then grinding to provide a 7i cutting edge which is not parallel to the back of the blade while the oblique line at the other end defines the butt of the finished blade.

10. A method of making rib-back surgical blades, which consists in reducing the body of a strip of steel by rolling with edge-relieved rolls, exerting a limited edgewise pressure on the strip by rolls having surfaces disposed at right angles to those of the reducing rolls and thereby forming an edge bead upon both edges of the strip which does not completely fill the relief cavity of the rolls and therefore has a rounded edge, forming curved perforations in the strip partially outlining oppositely arranged blanks with the back of each blank including a straight part of a marginal rib, hardening and tempering the perforated strip, then separating the blanks from the strip, each with an edge portion partially curved and partially straight, and finally grinding said edge portions to form a cutting edge.

MORGAN PARKER.

J. W. BROOKS LADD. 

